Fuel pump cylinder and piston



Jan. 29, 1952 c, E, S M S? 2,583,974

FUEL PUMP CYLINDER AND PISTON Original Filed Au 14, 1945 Patented Jan. 29, 1952 2,583,974 FUEL PUMP CYLINDER AND PISTON Caleb E. Summers, Orchard Lake, Mich.

Original application August 14, 1943, Serial No.

498,699, now Patent No. 2,414,617, dated January 21, 1947.

Divided and this application January 9, 1947, Serial No. 720,993

1 Claim.

The present invention relates to cylinders and pistons specifically for gasoline or similar light low viscosity fluids.

In impulse pumps for gasoline and the like, particularly when a high or moderately high pressure delivery is required, it is necessary that there be a very close and accurate fit of the piston in the cylinder, and in ordinary methods it is difiicult, expensive, and sometimes impossible to obtain such fits.

Among the objects of the present invention is a method of obtaining the necessary close fitting of the piston in its cylinder that will be inexpensive both in time and equipment.

Another object is a cylinder and piston produced by such method.

Further, even with the close fit obtainable by the present method, if very high delivery pressures are to be had, additional means for preventing leakage of the light liquid past the piston are desirable.

It is, therefore, also among-the objects of the invention to provide such additional means.

Still other objects and advantages will be apparent to those skilled in the art upon reference to the following description and the accompanying drawings in which Figure 1 is a central longitudinal sectional View of a cylinder and piston embodying the present invention.

Figure 2 is a section on line 2-2 of Figure 1.

The present application is a division of my copending application Serial No. 498,699, filed August 1%, 1943, now Patent No. 2,414,617, on Fuel Metering, and Injection Pumps, and Figure l of the present drawing is a part of Figure 1 of that application.

In the drawing, the cylinder l I of suitable material is shown as provided with a liner N5 of steel or other suitable material, which liner is provided outside and in with circumferential grooves I1 and I8. These grooves are of considerable width as shown and arranged so that there is a small overlapping. The inside of liner I6 is provided with a substantial coating I BA of silver, cadmium or tin, preferably the latter.

Fitted within the cylinder liner I6 is a piston 30, shown in the form of a rod, having at its rearward end a roller cam follower 32 adapted to coact with a cam 33. This cam 33 provides for the delivery or forward stroke of the piston 30 while the return or suction movement is through the action of a suitable spring 3|.

At the forward end of the cylinder II is fixed a member 20 having a pump chamber 2 I, an out:

2 let 25 controlled by a valve 26, and a valve 23 controlling an inlet 22.

As stated above, in pumps adapted to deliver light liquids, such as gasoline, it is necessary that the piston have as little clearance in the cylinder as is possible. So, in producing the present structure, the liner I6 is electroplated on the inside with one of the metals mentioned above, pref erably tin, to provide a coating sufficiently thick to reduce its inside diameter to a dimension slightly less than the diameter of the piston 30. The latter, or a special broach, is then forced into the cylinder and liner so that the excess of the soft metal is displaced by consolidation or partial removal or both, and substantially no piston clearance results.

This, in itself, will give good results in the use of the pump, but as a further prevention, of leakage past the piston, an oil inlet [6K leading to the central inside groove I8 is provided and oil under pressure is forced in.

The pressure of such oil should be somewhat higher than the average pressure built up in chamber 2| so that any movement of fluid past the piston is toward chamber 2| rather than away from it.

The grooves I1 and I8 are provided to prevent decrease in the inside diameter of the liner due to any greater contraction of the cylinder ll, if the latter should be made of metal having a much greater coefficient of expansion than that of the liner.

Now having described the invention and the preferred embodiment thereof, it is to be understood that said invention is to be limited, not to the specific details herein set forth, but only by the scope of the claim which follows.

I claim:

In a fuel pump of the cylinder and piston type, a body of metal having a relatively high coefficient of expansion, and a piston of relatively low coeffiicent of expansion, a sleeve lining mounted in said body and in which said piston is reciprocable, said sleeve being also of relatively low coefficient of expansion, means for maintaining piston clearance under varying temperature conditions, said means consisting of annular relieved portions inside and outside of said sleeve, said outer and inner relieved portions alternating longitudinally throughout the length of the sleeve and slightly overlapping.

CALEB E. SUMMERS.

(References on following page) REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Mattson Dec. 2, 1924 10 Number 4 Name Date Weaver July 27, 1926 Morgan Apr. 6, 1937 Towler et a1. Aug. 8, 1939 Ryder Jan. 23, 1940 Mancuso Nov. 5, 1940 Williams Sept. 12, 1944 Surtees Oct. 31, 1944 Kilchenmann Aug. 6, 1946 

